Process for the manufacture of bis-benzo-furanyl compounds

Abstract

Process for the manufacture of optically brightening bis-benzofuranyl compounds by cyclization of compounds of the formula ##STR1## in aprotic solvents and in the presence of alkali metal or alkaline earth metal carbonates.

What is claimed is: 
     
       1. Process for the manufacture of bis[benzofuranyl-(2)] compounds of the formula (I) ##STR11## in which B denotes a direct link or one of the following groups ##STR12## P, Q, P' and Q, independent of one another, are hydrogen or halogen atoms, lower alkoxy or phenyl, optionally functionally modified carboxy groups, or P and Q as well as P' and Q' together denote a fused benzene nucleus, which comprises subjecting compounds of the formula II ##STR13## in which B, P, Q, P' and Q' are as defined above and R denotes alkyl, aryl or aralkyl and X stands for an anion, in an aprotic solvent and in the presence of an alkali metal or alkaline earth metal carbonate to a cyclization reaction.     
     
     
       2. The process of claim 1, wherein sodium carbonate or potassium carbonate is used as cyclization agent. 
     
     
       3. The process of claim 1, wherein aromatic hydrocarbons substituted by alkyl groups or halogen atoms are used as aprotic solvent. 
     
     
       4. The process of claim 1, wherein chlorinated hydrocarbons such as chlorobenzene, o-dichlorobenzene or trichlorobenzene are used as aprotic solvent. 
     
     
       5. The process of claim 1, wherein the cyclization is carried out at temperatures of from 100° to 200° C., preferably 130° to 180° C. 
     
     
       6. The process of claim 1, wherein the cyclization is carried out while simultaneously distilling off the water formed from the carbonate. 
     
     
       7. The process of claim 1, wherein the cyclization is carried out while passing over a weak nitrogen current.